Neutralisation Reactions

Neutralisation is the chemical reaction between an acid and a base, which forms water and a salt. The general equation for a neutralisation reaction is:

Acid + basesalt + water

Another way to write this equation is with ions:

H+ + OHH2O

We use the word base instead of alkali because an alkali is a base that dissolves in water.

Insoluble bases, such as calcium hydroxide, cannot dissolve in water. This means that it can’t form an alkali. However, if you react it with an acid, it will still form salt + water.

Soluble bases, such as sodium hydroxide, can dissolve in water to form an alkali solution. The chemical equation for this reaction is:

Acid + alkali salt + water

Let’s look at an example:

In this example, hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water (H2O).

Remember:

In this case, we have:

  • Hydrochloric acid – which is the acid
  • Sodium hydroxide – which is the base (and also an alkali, as it’s a soluble base)

This forms:

  • Sodium chloride – which is the salt
  • Water – which is the remaining product

To name the salt produced, use the first part of the alkali (reactant) as the first word. This is ‘sodium’. The second part of the salt depends on the acid used in the reaction. Since we used hydrochloric acid, the second part of the name is ‘chloride,’ forming sodium chloride. This makes the equation:

Hydrochloric acid + Sodium hydroxideSodium chloride + Water

The symbol equation for this reaction is:

HCl + NaOHNaCl + H2O